1. Field of the Invention
This invention relates to 1,4-diazabicyclo[2.2.2]octanes and is more particularly concerned with novel processes for their preparation and certain novel 1,4-diazabicyclooctane diammonium dihalide intermediate compounds and novel dihaloalkylene diamine precursors therefor.
2. Description of the Prior Art
The outstanding ability of 1,4-diazabicyclo[2.2.2]octane (also known as triethylenediamine) and related compounds to catalyze the reaction of isocyanates with polyols to form urethanes and, also, the reaction between isocyanates and water to water-blow urethane foams, has long been recognized and utilized by those skilled in the polyurethane foam art; see "DABCO Triethylenediamine, Properties, Reactions and Applications", May 1971, Air Products & Chem. Inc., Wayne, Penna.
The commercial preparation of triethylenediamine, in the main, now requires the use of high temperature-high pressure type reactions which are not energy efficient processes. Typical of such processes is the thermal cracking of diethylenetriamine over a silica-alumina catalyst at 355.degree.-360.degree. C. (U.S. Pat. No. 2,937,176). Another typical process is the treatment of various piperazine stocks, including mixtures of reduction products from ethanolamine (i.e. aminoethylpiperazine, hydroxyethylpiperazine, diethylenetriamine and the like), with a tungsten-aluminum catalyst, or silica-alumina with ammonia at high temperature (e.g. 378.degree. C.); see U.S. Pat. Nos. 3,056,788, 3,120,526, and 3,231,573. Invariably, these methods lead to multi-product mixtures which require complex separation procedures including fractional distillation.
The preparation of triethylenediamine via ring closure of N-(.beta.-cyanoethyl)-N'-(.beta.-chloroethyl)piperazine in a low temperature process has been reported; see U.S.S.R. Pat. No. 519,416 (C.A. 86, 29873y).
It has now been discovered that triethylenediamine and certain derivatives can be prepared in high yields and in a low temperature and energy efficient process based on simple and readily available ethylene diamines thereby eliminating the need for preparing a piperazine starting material. Furthermore, the present process gives rise to but a single product and in a high state of purity thereby obviating the need for complex and expensive separation procedures required by the prior art methods.
After the present invention was made there has been published (Khim. Geterotsikl. Soedin. 1978, (4), page 548-50, published Apr. 5, 1978) a process for the preparation of triethylenediamine by treatment of N,N'-bis(.beta.-cyanoethyl)ethylene diamine with ethylene oxide to give the diol followed by chlorination to yield N,N'-bis(.beta.-chloroethyl)-N,N'-bis(.beta.-cyanoethyl)ethylene diamine which is cyclized and decyanoethylated by boiling in dimethylformamide.